Master Gardeners: Houseplants are nature’s air filters

<p>English ivy, or Hedera helix, is a commonly found houseplant that will help filter your home's air.  |  Julie Moore/submitted</p>

English ivy, or Hedera helix, is a commonly found houseplant that will help filter your home's air.  |  Julie Moore/submitted

Houseplants add color and charm in our homes, acting as pleasing design elements to our rooms. However, houseplants should not only be appreciated for their good looks.  All year long they silently work on our behalf as air filters.

As houseplants photosynthesize and grow they remove carbon dioxide from the air and in turn release oxygen. A study, completed by NASA several years ago, found that houseplants are also capable of removing some toxic chemicals from the air. The plants in the study were lower-light requiring varieties that, fortunately, grow well in our homes. English ivy (Hedera helix), Peace Lily (Spathiphyllum ‘Mauna Loa’), Gerbera Daisy (Gerbera jamesonii), Mother-in-law’s tongue (Sansevieria laurentii) and Marginata (Dracena Marginata) were some of the plants used. All are typically available at florists, big box stores and even supermarkets.

The NASA Clean Air Study noted that the most efficient toxin reducing houseplants tested were those “allowing maximum contact between the soil-root zone and the air.” In other words, removing leaves of the plant at the soil line allowed the most amount of air to be in contact with the soil-root zone area, resulting in the best air filtration.

March is a good time to take steps to prepare your houseplants for the active growing season they have entered. The longer daylight at this time of year awakened their internal clocks causing them to exit a winter’s rest. Replacing a spent growing medium will boost your plant’s ability to thrive. Use sterile mixes that are free of insects and disease. Re-set the plant in the pot at the same depth that it was grown at for success whether using the same container or a larger one.

This season of active growth is when house plants can be fertilized. Once every one to three months should suffice. A balanced granular fertilizer for houseplants works well and is mixed with water. Slow release fertilizer pellets placed on the soil surface are also effective and last for several months. Always follow label directions.

Plants get dusty and benefit from having their surfaces cleaned. Lukewarm water from a kitchen sink sprayer works well for smaller plants. Wipe larger plants clean with a soft, damp cloth or try spraying clean in the tub with a handheld shower head.

 Visit for all of your houseplant questions.

Email your home garden and lawn questions to or phone the Master Gardener Helpline at 630/955-1123. Visit our website at  

Julie Moore has been a Master Gardener volunteer with the University of Illinois Extension in DuPage County for 10 years and has a degree in Ornamental Horticulture from the University of Illinois.